Abstract: Various systems and methods of monitoring laser safety by sensing contact of the system with a sample are provided. The system includes a focusing element for focusing an incident light from a laser light source onto a sample, an optical element having a collection zone for collecting a signal from the sample, a reflected light sensor for sensing a reflected light from the sample, wherein the reflected light sensor is located outside the collection zone of the optical element and on an inner surface of a housing of the system, an electrical circuit operably connected to the reflected light sensor and the laser light source and configured to control power to the laser light source in accordance with the reflected light sensed by the reflected light sensor and a spectral analyzer for processing the signal. Methods and other systems are also described and illustrated.

Abstract: An apparatus consisting of stacked slab waveguides whose outputs are vertically staggered is disclosed. At the input to the stacked waveguides, the entrances to each slab lie in approximately the same vertical plane. A spot which is imaged onto the input will be transformed approximately to a set of staggered rectangles at the output, without substantial loss in brightness, which staggered rectangles can serve as a convenient input to a spectroscopic apparatus. A slit mask can be added to spatially filter the outputs so as to present the desired transverse width in the plane of the spectroscopic apparatus parallel to its dispersion.

Abstract: An apparatus consisting of stacked slab waveguides whose outputs are vertically staggered is disclosed. At the input to the stacked waveguides, the entrances to each slab lie in approximately the same vertical plane. A spot which is imaged onto the input will be transformed approximately to a set of staggered rectangles at the output, without substantial loss in brightness, which staggered rectangles can serve as a convenient input to a spectroscopic apparatus. A slit mask can be added to spatially filter the outputs so as to present the desired transverse width in the plane of the spectroscopic apparatus parallel to its dispersion.

Abstract: An apparatus is presented for stabilizing an optical, thermal, and mechanical interface between a spectroscopic and/or imaging system and a biological sample. The apparatus includes a window retainer having a retainer surface and a well. The retainer surface surrounds the well. Further, the retainer surface is substantially planar. An optical window is located in the well. The optical window comprises a first and second surface. The second surface is in contact with the window retainer. The first surface is substantially flush with the retainer surface. The apparatus further includes an attachment mechanism coupling the window retainer to the biological sample such that a fluid, gel, adhesive or elastomer interposed between the optical window and the biological sample is trapped in the well.

Abstract: An apparatus consisting of two pairs of identical lenses which is suitable as a compound objective lens for high numerical aperture imaging is disclosed. The compound lens also has a wide field of view as a fraction of the compound lens focal length. By suitable choice of lens materials, well corrected near infrared imaging can be achieved. When two such compound lenses together with a diffraction grating are assembled into a spectrometer, excellent wavelength resolution in the near infrared can also be obtained.

Abstract: An apparatus is disclosed wherein laser radiation illuminates a sample using all reflective optics and wherein in-elastically scattered light from the sample is collected using the identical elements. The apparatus obviates the problem of contaminating the laser radiation with unwanted spectra from transmissive optics while providing very high rejection of the laser radiation with respect to the in-elastically scattered light. In addition, the apparatus can collect and launch light with high numerical aperture and large field of view.

Abstract: An apparatus is presented for stabilizing an optical, thermal, and mechanical interface between a spectroscopic and/or imaging system and a biological sample. The apparatus includes a window retainer having a retainer surface and a well. The retainer surface surrounds the well. Further, the retainer surface is substantially planar. An optical window is located in the well. The optical window comprises a first and second surface. The second surface is in contact with the window retainer. The first surface is substantially flush with the retainer surface. The apparatus further includes an attachment mechanism coupling the window retainer to the biological sample such that a fluid, gel, adhesive or elastomer interposed between the optical window and the biological sample is trapped in the well.

Abstract: The concentration of analytes in a complex mixture can be ascertained by spectroscopic measurement, even if the spectra of substances other than the analyte overlap with that of the analyte. Both independently measured concentrations of the analyte in a training set and of the analyte spectrum are used. Variances in the spectral data attributable to the analyte are isolated from spectral variances from other causes, such as compositional changes associated with different samples that are independent of the analyte. For the special case of noninvasive glucose measurements on the skin of biological organisms, the volume averaged glucose in the sample is predicted from the blood glucose. A test for over-fitting of the data is also described.

Abstract: An apparatus comprising an optical window transmits both an excitation beam to a sample and scattered light from the sample which is within the angular range of the collection optics. Scattered light from the sample outside the angular range of the collection optics is re-directed back to the sample by reflection from one or more surfaces of the apparatus. As a result, the magnitude of scattered light collected is increased.

Abstract: An apparatus is presented in which a sample can be accurately repositioned in a spectroscopic and/or imaging apparatus upon multiple insertions, and where the apparatus can be worn by living subjects for extended periods of time. The apparatus additionally reduces the temperature increase and stabilizes the temperature of the sample upon irradiation with an optical source of excitation. Additionally, the apparatus stabilizes the pressure and critical optical properties of the sample and its interface with the apparatus. Alternatively or additionally, the apparatus can be used to alter and/or substantially reduce fluorescence from targeted fluorophores in the sample.

Abstract: The concentration of analytes in a complex mixture can be ascertained by spectroscopic measurement, even if the spectra of substances other than the analyte overlap with that of the analyte. Both independently measured concentrations of the analyte in a training set and of the analyte spectrum are used. Variances in the spectral data attributable to the analyte are isolated from spectral variances from other causes, such as compositional changes associated with different samples that are independent of the analyte. For the special case of noninvasive glucose measurements on the skin of biological organisms, the volume averaged glucose in the sample is predicted from the blood glucose. A test for over-fitting of the data is also described.

Abstract: The concentration of analytes in a complex mixture can be ascertained by spectroscopic measurement, even if the spectra of substances other than the analyte overlap with that of the analyte. Both independently measured concentrations of the analyte in a training set and of the analyte spectrum are used. Variances in the spectral data attributable to the analyte are isolated from spectral variances from other causes, such as compositional changes associated with different samples that are independent of the analyte. For the special case of noninvasive glucose measurements on the skin of biological organisms, the volume averaged glucose in the sample is predicted from the blood glucose. A test for over-fitting of the data is also described.

Abstract: An apparatus for increasing the blood perfusion in skin by elevating the temperature, and for providing superior heat sinking to the skin of thermally dissipative devices is disclosed. The increased perfusion gives rise to improved thermal transport properties near the site of elevated temperature which is advantageously used by thermally connecting the dissipative devices to the skin. The heat generated by the thermally dissipative devices can supplement or replace separate heating elements to elevate the skin temperature. Alternatively, thermal isolation of the heated area of the skin from the heat sinks of the dissipative devices can minimize the temperature of the skin in contact with the heat sinks.

Abstract: An apparatus consisting of stacked slab waveguides whose outputs are vertically staggered is disclosed. At the input to the stacked waveguides, the entrances to each slab lie in approximately the same vertical plane. A spot which is imaged onto the input will be transformed approximately to a set of staggered rectangles at the output, without substantial loss in brightness, which staggered rectangles can serve as a convenient input to a spectroscopic apparatus. A slit mask can be added to spatially filter the outputs so as to present the desired transverse width in the plane of the spectroscopic apparatus parallel to its dispersion.

Abstract: An apparatus is disclosed wherein laser radiation illuminates a sample using all reflective optics and wherein in-elastically scattered light from the sample is collected using the identical elements. The apparatus obviates the problem of contaminating the laser radiation with unwanted spectra from transmissive optics while providing very high rejection of the laser radiation with respect to the in-elastically scattered light. In addition, the apparatus can collect and launch light with high numerical aperture and large field of view.

Abstract: An apparatus consisting of two pairs of identical lenses which is suitable as a compound objective lens for high numerical aperture imaging is disclosed. The compound lens also has a wide field of view as a fraction of the compound lens focal length. By suitable choice of lens materials, well corrected near infrared imaging can be achieved. When two such compound lenses together with a diffraction grating are assembled into a spectrometer, excellent wavelength resolution in the near infrared can also be obtained.

Abstract: An apparatus for enhancing the selectivity for spectroscopic measurements of analytes in a turbid medium is described. In one example, spatial filters are used to select only certain radii from the medium to be imaged. This selection is accomplished by placing an optical obstruction on the surface of the medium or at an image plane of the surface later in the optical imaging system. In one implementation, this is achieved by placing a fiber bundle at an image plane of the collecting optical system and then using a spacer of appropriate size at the center of the fiber bundle to act as a central obstruction.

Abstract: A method is proposed whereby photo-bleaching is used not only to change the absorption and fluorescence of a sample but is also employed to change its scattering characteristics. When the compounds which are bleached are contained in regions wherein the real part of the index of refraction is greater than or equal to the average index of the medium, the bleaching will result in reduction in the scattering at wavelengths longer than the wavelength of the bleaching source. This reduction can be useful in measuring the concentration of analytes located at significant depths within turbid media.

Abstract: The concentration of analytes in a complex mixture can be ascertained by spectroscopic measurement, even if the spectra of substances other than the analyte overlap with that of the analyte. Both independently measured concentrations of the analyte in a training set and of the analyte spectrum are used. Variances in the spectral data attributable to the analyte are isolated from spectral variances from other causes, such as compositional changes associated with different samples that are independent of the analyte. For the special case of noninvasive glucose measurements on the skin of biological organisms, the volume averaged glucose in the sample is predicted from the blood glucose. A test for over-fitting of the data is also described.

Abstract: An apparatus is presented in which a sample can be accurately repositioned in a spectroscopic and/or imaging apparatus upon multiple insertions, and where the apparatus can be worn by living subjects for extended periods of time. The apparatus additionally reduces the temperature increase and stabilizes the temperature of the sample upon irradiation with an optical source of excitation. Additionally, the apparatus stabilizes the pressure and critical optical properties of the sample and its interface with the apparatus. Alternatively or additionally, the apparatus can be used to alter and/or substantially reduce fluorescence from targeted fluorophores in the sample.